Long-term performance of hybrid MiC buildings considering concrete creep and shrinkage

With the completion of several pilot projects in Hong Kong, Modular Integrated Construction (MiC) is being promoted to boost the productivity and cope with the labour shortage in the local construction industry. However, the possible adverse effects of differential axial shortening due to the time-dependent behaviour arising from concrete creep and shrinkage will only become obvious after a long time. In this study, simplified numerical models are established based on typical hybrid MiC buildings in Hong Kong. Time-dependent analyses considering the creep and shrinkage of concrete are carried out. The construction schedules of the pilot MiC projects are used as a reference to model the staged construction. The results for a 20-storey hybrid MiC building indicate, owing to the concrete creep and shrinkage, noticeable stresses at the module-to-wall connections at the corners of core walls 30 years after construction. The compressive stresses at the bottom of the steel MiC modules will increase substantially over time, which could reduce the amount of material strength that can be utilised by other loads. Hence checking of long-term performance should be conducted at the design stage, particularly focusing on the connections.